You see, people (e.g. Erik) complain that the i8255 is too slow. However, it's faster than the standard 803x. It does, of course, require that an external memory bus be available. If no such bus is otherwise required, it seems silly to me to use an i8255 since it requires two external ports to do the job and doesn't really provide more I/O than that if one needs the "features."

However, it allows tightly coupled I/O, by menas of its handshaking capability, that might not be implementable on a 12 MHz 12-clocker becuase of its slow execution rate.

The point I was trying to make is that, contrary to what Erik has frequently said, the i8255 can and will work just fine with the "standard" 12-clockers without any problem and can work with some faster MCU's so long as one doesn't violate the timing requirements. It does things that are difficult to generate in SSI/MSI logic, yet only occupies a PLCC-44 or DIP-40. It's available, apparently, in India and throughout Asia, though not so much around here in the U.S.

Why not help the guys who want to use it? It doesn't cost US anything.

RE